Sulfite antistain bath for multilayer color film



Patented July 5, 1949 NITED STATES i iilTENT OFFICE SULFITE ANTISTAIN BATH FOR MULTI- LAYER COLOR FILM Delaware No Drawing. Application November 8, 1945, Serial No. 627,533

9 Claims.

This invention relates to photographic antistain baths, to anti-stain baths employed in multi-color photography, and especially to nonstaining baths for the washing of multi-color photographic material following the fixing treatment.

It is known that in the processing of multicolor reversible film and multi-color reversible film coated upon a white opaque support, the exposed film or exposed White opaque, is first developed with a normal black and white developer to produce a negative image. After development, the black and white negative material, without being fixed, is exposed to general illumination, followed by a second development with a color-forming developer. During the first and second development the silver-halides in all the layers are reduced to metallic silver. After the second development, the material is cleared in running water, hardened in an aqueous solution consisting of either chrome or potassium alum, and then washed in running water. After the latter treatment, the silver present in all the layers formed during the first and second development is converted into a salt by any of the known silver-salt formers, commonly known as bleaching baths, and the silver-salt thus formed is then removed by dissolving it in a silver-salt solvent such as, for example, hypo. The mate-- rial is then washed for a long period of time and then dried.

Prior to the washing operation it is essential that the residual second or color developer and bleach solutions be removed, otherwise stains will be formed during the drying operation, which are particularly noticeable in the white area, In order to prevent this staining, an extended final washing time in running water of from fifteen minutes to two hours, has been proposed. Even if this proposal be adopted, stains are nevertheless formed after the drying operation. It is believed that the staining results from the oxidation of traces of. the color developer retained in the layers of the material following color-forming development, which then react with the unused color-former.

An object of the present invention is to eliminate excessive washing time of color developer multi-color photographic material while preventing the formation of stain.

A further object of the invention is a final rinse bath which clears undesirable matter from a multi-color photographic material in a short time while avoiding staining.

Other objects and features of the invention will become more apparent as the description proceeds.

We have found that the above objects are accomplished by employing, as a final rinse bath, an aqueous solution containing a small quantity of a water-soluble alkali sulfite such as ammonium, potassium, or sodium sulfite, bisulfite, and meta-bisulfite. This discovery makes it possible to considerably reduce the final washing time. The concentration of the alkali sulfite may vary from as little as 0.01% to as high as 1%. Amounts higher than 1% give little improvement in stain prevention from a practical standpoint and, accordingly, concentrations ranging from between 0.1% to 1% are most desirable.

The photographic multi-layer materials, which may be processed with the anti-stain bath of the present invention, are color reversible film, color negative film, color reversible printing material coated on a white opaque base, and color positive printing material coated on paper, irrespective of whether the dyestuff images are produced with color-formers present in the emulsion or by a selective second exposure followed by color development. The color reversible film consists of an integral tripack emulsion coated on the usual clear cellulose acetate or nitrate film base. Each of the emulsions are sensitized to one of the primary colors of light; namely, blue, green, and red. The top layer is blue sensitive. A filter layer, yellow in color and blue absorbing, lies under the top layer. Below this filter layer, lies a green sensitive emulsion layer, and below this is a red sensitive emulsion layer. Each of the three I silver-halide emulsion layers contain dye-forming compounds which unite during the development of silver image in an aromatic amine developing agent to form a dye with the oxidation product of the developing agent, or may be free from color-formers in which case the film is processed with the color-formers in the color developers by the selective second exposure and color development method as described in United States Patents 1,897,866; 1,900,870; 1,928,709 and 1,980,941. The color negative film is made up in the same manner as the color reversible film, with the exception that it may contain a layer of clear gelatin between the red sensitive layer and the green sensitive layer. The color reversible White opaque material is prepared in the same manner as color reversible film and the color negative film, with the exception that the base consists of an opaque white film. The color paper is also constructed in the same manner as the color reversible film and the color negative film, with the exception that the emulsion is coated on a baryta coated paper base.

As silver is formed during development, it must be removed after color development by treatment in a bleach, followed by treatment'fin a bath of sodium thiosul fat-e according to usual practice. A yellow dye is formed in the blue sensitive emulsion; a magenta dye is formed in the green sensitive emulsion; and a cyan dye is ijormed in the. red sensitive emulsion. Combinations of these three printing primaries will produce all of the other colors in the finished film'or print. Suitable methods for the preparatioirqf togr'aphic multilayer materials have been described 'in the literature relating to color photography, and are, therefore, not described here.

The following examples describe in detail methods for accomplishing the above obj ects,-b ut it is to be understood that they are inserted merely for the purpose of illustration and are not to be construed" as limiting the'scope'of the invention.

Example I A 4" x 5 full color transparency sheet of color film was printed by contact on; two if x 5" sheets of color reversible white opaque mm,

e t et of '7 9 r ve l white opaque film were first developed" for twelve minutes at 68 F. in a developer of the following composition:

p-monomethy-lamine-mphenol sulphate grams 3 Sodium sulfite f do' 50! Hydroquinone do.. 6 Sodium carbonate (monohydrate) do 40 Sodium thiocyanate do 2 Potassium bromide do 2. Water to make up liters 1 The devolope'dfilm was short stopped for 3 minutes at 68 F., in a 5% aqueous solution of sodium bisulfite.

The film was washedfor 2 minutes in running water at 68 F., and then color deyelopedfor minutes at 6 8 F., in a developer of the following composition:

p-Aminodiethylaniline HCl grams 4' Sodium sulfite' do 5 Hydroxylamine HCl do 2 Sodium carbonate do 40 Potassium bromide do 1 Water to make up liters 1 The color developed film was rinsed for 4 grams" 100 Potassium bromide ..d0 15 Disodium phosphate do 40 Sodium bisulfate ..do Water to make up 1iters 1 T bleached. film we ashe o 5. minu e at 68 F. and then fixed fort, n i nutes 'in a solution of the following composition:

After fixing, the material was washed for 10' minutes in running water at 68 F.

After the final wash, one print was allowed to dry while the other was rinsed for 2 minutes in a 0.1% solution of sodium sulfite and then allowed to dry. At this point the prints appeared identical. After normal drying, the print rinsed in the sodium sulfite solution showed brighter colors and more brilliant highlights than the print given only awater wasli'for 15-20 minutes.

When' the drying was carried out under conditions of high h'umidity so that the drying time was extended for several hours the water rinsed print showed even greater highlight stains while the print rinsedin'sodium sulfite solution did not change.

Easample II Example I was repeated with the exception that the colored photographic. multilayer material employed was color paper, and the, final rinse bath was a 0.01% solution of sodium bisulfite, instead of a 0.1% solution of sodium sulfite. The, color printwashed in water showed objectionable, stains after drying, While they print treated'with the solution of sodium bisulfite was clear and un stained.

Example III Example I was repeated with the exception that the final rinse bath was a .01 solution oi sodium metabisulfite instead of; a 0.1 solution of-sodium sulfite. After fixin and washing, the. color print rinsed in plain water showed-ob jectionablestains, while the print treated with; the" sodium metabisulfite solution was clear and unstained.

From the above, examples it is manifest that the multi-layer photographic material rinsedin plain water shows marked staining upon dryingof-said material. This staining occurs especially, under slow drying conditions and is probably due to-the coupling of the slow oxidation product ofthe color developer with a residual color-coupler presentin; one, or more layers.

In-place of the Water-soluble alkali sulfite solutions referred; to above, afixing bath'consisting Of-hypo. and borax-containing an alkali sulfitein quantities'ranging fromabout 3 to 8 grams per liter, may also bra-employed.

A typical composition of a fixer employing an; alkali sulfite is as follows:

Hypo rams 200. B PQ -".--,"7---"-.-, Alkali sulfite do 3-18" Water to make up liters 1 The fixing bath as above prepared may'be employed in place of'the normal fix'erand prior to' the washing operation after fixing" the prints, and given a normal Wash of 10' to 20 minutes and allowed to dry.

After drying; the prints will have a clearer highlight than the prints fixed in the usual fixin'g bath ahdthen washed forlOto 20 minutes."

The above specific examples are to be'regarded as merely illustrative of the'invention, and not in anysense restrictive. It will be" obvi'ousto anyone skilled in the art that many modificatations such as substituting equivalent material and varying the proportions of materials'used are within the spirit and scope of-the invention as defined in the appended claims.

We claim:

1; In a'process' of color'photo'graphy-the method of preventing stains on color images selected from the class consisting of indophenol and azomethine dyes, produced in a multilayer color film by color-forming development which comprises washing said film after exposure, color developing, bleaching and fixing, but prior to drying with an aqueous solution consisting of water and an alkali sulfite.

2. In a process of color photography the meth- 0d of preventing stains on color images selected from the class consisting of indophenol and azomethine dyes, produced in a multilayer color film by color-forming development which comprises washing said film after exposure, color developing, bleaching and fixing, but prior to drying with an aqueous solution consisting of water and sodium sulfite.

3. In a process of color photography the method of preventing stains on color images selected from the class consisting of indophenol and azomethine dyes, produced in a multilayer color film by color-forming development which comprises washing said film after exposure, color developing, bleaching and fixing, but prior to drying with an aqueous solution consisting of water and sodium bisulfite.

4. In a process of color photography the method of preventing stains on color images selected from the class consisting of indophenol and azomethine dyes, produced in a multilayer color film by color-forming development which comprises washing said film after exposure, color developing, bleaching and fixing, but prior to drying with an aqueous solution consisting of water and sodium metabisulfite.

5. The method according to claim 1 wherein the concentration of the said alkali sulfite ranges from .01% to 1%.

6. In a process of producing color photographic images selected from the class consisting of indophenol and azomethine dyes, in a multilayer color film by exposing the film, color-forming developing the same, bleaching, fixing and washing, the improvement which comprises avoiding the formation of stain, after the bleaching, fixing, and washing operation, by rinsing the said film with an aqueous solution consisting of water and an alkali sulfite.

7. In a process of producing color photographic images selected from the class consisting of indophenol and azomethine dyes, in a multilayer color film by exposing the film, color-forming developing the same, bleaching, fixing and washing, the improvement which comprises avoiding the formation of stain, after the bleaching, fixing, and washing operations, by rinsing the film with an aqueous solution consisting of water and sodium sulfite.

8. In a process of producing color photographic images selected from the class consisting of indophenol and azomethine dyes, in a multilayer color film by exposing the film, color-forming developing the same, bleaching, fixing and washing, the improvement which comprises avoiding the formation of stain, after the bleaching, fixing, and washing operations, by rinsing the film with an aqueous solution consistingof water and sodium bisulfite.

9. In a process of producing color photographic images selected from th class consisting of indophenol and azomethine dyes, in a multilayer color film by exposing the film, color-forming developing the same, bleaching, fixing and Washing, the improvement which comprises avoiding the formation of stain, after the bleaching, fixing, and washing operations, by rinsing the film with an aqueous solution consisting of water and sodium metabisulfite.

HAROLD C. HARSH. JAMES E. BATES.

REFERENCES CITED The following referenlces are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,617,434 Binder Feb. 15, 1927 1,753,059 Murray Apr. 1, 1930 1,930,140 Becker Oct. 10, 1933 2,059,884 Mannes Nov. 3, 1936 2,203,903 Ham June 11, 1940 2,301,387 Evans Nov. 10, 1942 2,323,481 McQueen July 6, 1943 2,334,658 Vittum Sept. 11, 1945 OTHER REFERENCES Clerc, Photography Theory and Practice, 2d edition, 1937, published by Sir Isaac Pitman and Sons Ltd., pages 236 and 237 cited. 

